Lock stitch sewing machines



Dec. 21, 1965 w. c. VAN NESS LOCK STITCH SEWING MACHINES 3 Sheets-Sheet 1 Filed Aug. 30, 1963 illr r a William C. Van Ness mm mm vm ATTORNEY WITNESS M qwm 1965 w. c. VAN NESS LOCK STITCH SEWING MACHINES 5 Sheets-Sheet 2 Filed Aug. 30, 1963 INVENTOR. William C. Van Ness WI TNESS Z TTORNE Y D 1965 w. c. VAN NESS LOCK STITCH SEWING MACHINES 3 Sheets-Sheet 5 Filed Aug. 30, 1963 INVENTOR. Wi/iiam C. Van Ness Fif? BY Wax! Q ATTORNEY WITNESS Maw 9 United States Patent O 3,224,397 LOCK STHTCH SEWING MACIHNES William C. Van Ness, Parsippany, NJ, assignor to The Singer Company, New York, N.Y., a corporation of N ew Jersey Filed Aug. 30, 1963, Ser. No. 305,671 4 Claims. (Cl. 112-154) This invention relates to lock stitch sewing machines, and more particularly, to a novel and improved arrangement in a lock switch sewing machine for producing lock stitches which are resilient or extensible lengthwise of the seam.

Conventional lock stitches (Federal Stitch Type 301) comprise a needle and a bobbin thread concatenated at each needle penetration, with successive needle penetrations spaced in one direction along the seam and with the threads extending directly between successive needle penetrations one above and the other beneath the work fabric. Beyond the resiliency of the thread itself, such conventional lock stitches provide practically no extensibility lengthwise of the seam. Conventional lock stitches, therefore, when applied to fabrics which possess considerable extensibility such as knit goods or the like, are out of keeping with the resilient character of the goods and will noticeably restrict the natural form fitting and drape characteristics of the fabrics. A conventional inextensible lock stitch seam if applied to a resilient fabric is also liable to rupture should an abrupt load be applied to the seamed fabric.

Since the non-raveling feature of a lock switch seam is frequently desired in resilient extensible fabrics such as knit goods, the seam provided by the present invention is particularly advantageous. With this invention the seam extensibility is obtainable simply by the addition to a conventional lock stitch sewing machine of a conveniently compact drive unit for jogging the needle alternately forwardly and rearwardly in the line of work feed. The resulting lock stitches thus periodically overlap so that the points of needle penetration of the overlapped stitches will converge when the fabric is thereafter stretched and the lock stitch seam will thus be free to extend with the fabric.

The novel mechanism of this invention provides for convenient selection by the operator of the degree of extensibility of the resulting lock stitch seam.

This invention also provides for novel handling and guiding of the sewing threads at the stitching point maintaining each stitch not only identical in appearance but also separate and distinct so as to preserve uniformity of extensibility throughout the resulting seam.

In the accompanying drawings of a preferred embodiment of this invention:

FIG. 1 represents a vertical cross sectional view of a sewing machine having the features of this invention applied thereto,

FIG. 2 represents a head end elevational view of the sewing machine of FIG. 1 with portions of the work support and throat plate broken away,

FIG. 3 is a cross sectional view taken substantially along line 3-3 of FIG. 1,

FIG. 4 represents an enlarged top plan view of the sewing machine presser foot viewed from line 4--4 of FIG. 1,

FIG. 5 represents an enlarged top plan view of a portion of the presser foot of FIG. 4 including a work fabric being stitched and the sewing machine needle and needle thread as the needle is jogged forwardly,

FIG. 6 represents an enlarged top plan view of a portion of the presser foot similar to that of FIG. 5 but showing the position of the needle and needle thread as the needle is jogged rearwardly, and

3,224,397 Patented Dec. 21, 1965 FIG. 7 represents a quasi-diagrammatic cross sectional view of work fabrics and the sewing threads concatenated into resilient lock stitches therein by the sewing machine of this invention.

Referring to the drawings, 10 indicates the bed of a sewing machine of which the upper surface 11 provides a work support for fabrics to be stitched. A throat plate 12 is set into the bed providing a continuation of the work supporting surface and formed with an elongate needle aperture 13 as well as with feed dog slots 14. Rising from the bed 10 is a standard 15 merging with a bracket arm 16 overhanging the bed and terminating in a sewing head 17 above the throat plate 12. A main shaft 18 journaled in the bracket arm has secured for rotation therewith a crank 19 embraced by a take-up lever 20 and by a drive link 21 pivoted on a stud 22 clamped on a needle bar 23.

The needle bar 23 is endwise slidable in a needle gate 24 which is journaled on a fulcrum pin 25 held in the bracket arm 17 by set screws 26. The fulcrum pin 25 is fixed in the bracket arm on an axis perpendicular to the feed dog slots 14 and elongated needle aperture 13 in the throat plate 12 so that the needle gate will swing in a plane parallel thereto. A needle 27 clamped on the needle bar will thus be reciprocated endwise by the crank 19 and can be jogged lengthwise of the elongated needle aperture 13 as the needle gate is swung. A pin 28 secured by a fastening screw 29 in a split clamp on the needle gate is embraced by a slide block 30 which is pivoted at one end of a drive link 31 secured by the clamp screw 32 to a rock shaft 33 journaled in a bushing 34 in a bracket arm partition 35 at the juncture of the bracket arm and sewing head for swinging the needle gate in response to oscillation of the rock shaft 33.

Indicated at in the drawings is a loop taker of the type referred to in the art as a rotary hook disposed beneath the throat plate 12 for cooperation with the needle 27 in the formation of lock stitches. The loop taker 40 is fast on a bed shaft 41 and is driven from the main shaft 18 by bevel gear sets 42 and 43 and a vertical shaft 44 in the standard preferably at two revolutions for each reciprocation of the needle.

Referring to FIG. 2, a work feeding mechanism of the drop feed variety is also arranged in the bed and comprises a feed dog working upwardly through the feed dog slots 14 in the throat plate and carried by a feed bar 51. The feed bar is pivoted as at 52 at one extremity to a rock arm 53 fast on a feed advance rock shaft 54 journaled lengthwise in the bed. At the other extremity, the feed bar is pivotally connected by a link 55 to a rock arm 56 on a feed lift rock shaft 57 journaled lengthwise in the bed. Referring to FIG. 1, the feed lift rock shaft is operated by a pitman 58 in the standard from a feed lift eccentric 59 on the main shaft 18 while the feed advance rock shaft is operated by a pitman 60 in the standard from a feed advance eccentric 61 on the main shaft. The feed advance eccentric is adjustable as to eccentricity to vary the feed stroke of the feed dog and thus the increment of work feed during each needle bar reciprocation. For eccentricity adjustment, the feed advance eccentric 61 may be constructed in accordance with the United States patent of W. Myers, No. 2,053,968, September 8, 1936. Eccentricity of the eccentric 61 is adjusted by the operator by depressing a spring loaded plunger 62 carried on the bracket arm into locking engagement with a notched adjusting flange 63 associated with the eccentric 61 and then turning a balance wheel 64 on the main shaft until a selected eccentricity and corresponding stitch length is attained.

As illustrated in FIGS. 2 and 4, the feed dog 50 is opposed by a presser foot 66 carried by a presser bar 67 in the bracket arm and biased downwardly by a coil spring 68.

Referring to FIGS. 1 and 3, the mechanism for imparting needle jogging motion is carried on a plate 80 secured by .screws 81 covering an opening 82 in the top of the bracket arm 17. Spaced bearing bosses 83 are secured to the plate 80 by screws 84 and sustain a stud shaft 85 in substantial parallelism with the main shaft 18. Fixed on the stud shaft 85 is a gear wheel 86 disposed in mesh with a gear 87 on the main shaft to drive the stud shaft at one half the speed of the main shaft. Also fixed on the stud shaft 85 is-an adjustable eccentric 88 which is of a type similar to the feed advance eccentric 61 and includes a notched adjusting flange 89 by which the eccentric 88 may be adjusted as to eccentricity. The operator may adjust the eccentric 88 by depressing a plunger 90 into engagement with the notch in the adjusting flange 89 and turning the balance wheel 64 until a selected eccentricity is attained. The plunger 90 is urged upwardly by a spring 91 and is constrained in place on the plate 80 by a cover 92 secured by screws 93 to the plate 80.

The adjustable eccentric 88 is embraced by a pitman 94 I which is pivoted as at 95 to a rock arm 96 on the rock shaft 33.- The range of adjustment of the eccentricity of the needle jogging eccentric 88 together with the kinematics of the linkage 94, 96, 31, 25, 24 for swinging the needle gate is preferably such as to provide for an increment of needle jogging during each needle reciprocation which is greater than the increment of work feed. Since the stud shaft 85 is turned at half the speed of the main shaft 18, the needle will be jogged prior to one stitch in the direction of work feed and prior to the next stitch in a direction opposite that of the work feed. FIG. 7 illustrates the resulting stitch formation when the needle jogging amplitude is selected at approximately one and one half times the stitch length provided by the Work feeding mechanism. The sequence of needle penetrations in FIG. 7 is A, B, C and D, the needle being jogged into a forward position, i.e., to the left as viewed in FIG. 2 at needle penetrations A and C and in a rearward position at needle penetrations B and D. When the needle is jogged in the direction of work feed a backward stitch A, B or C, D will be made of which the length will be the difference between the needle jogging increment and the work feeding increment. When the needle is jogged in a direction opposite that of the work feed, a forward stitch B, C will be made of which the length will be the sum of the needle jogging increment and the work feeding increment.

The extensibility of the seam illustrated in FIGS. 5, 6 and 7 arises from the fact that backward stitches A-B, C-D etc. can shorten when the work fabric is elongated. In FIG. 6, for instance, elongation of the seam would involve the shift of point B toward A, D toward C, F toward E etc.

Manifestly, such resilience of the seam is possible only when the threads of each stitch lie separately along the fabric as illustrated in FIGS. 5, 6 and 7. Should the needle 27 in making a backward stitch C-D, E-F etc. penetrate the thread of the previous forward stitch B-C, D-E etc., the stitches would become locked together and extensibility lost.

It is a feature of this invention that each of the stitches of the seam are maintained separate and needle penetration of any of the previous stitches is positively prevented by means of a stitch deflecting finger 100 secured by screw 101 to the presser foot 66. As illustrated in FIG. 4, the stitch deflecting finger 100 spans the elongated needle aperture 13 in the throat plate 12. As illustrated in FIGS. 5 and 6, the stitch deflecting finger 100 is arranged between the limits of needle jogging motion i.e., within the increment of needle jogging motion along the needle aperture. As a result, the needle thread of each stitch is formed over the stitch deflecting finger 100. The leading edge of the st tch d fle i g nger 1.00 is preferably ta ered as at 102- providing an incline which in response .to the work feed draws the threads which are laid over the finger outwardly toward the free extremity of the finger as the work feed progresses.

The presser foot opposite the free extremity of the stitch deflecting finger 180 may be grooved as at 103 to provide clearance for the threads to pass about the finger. The free extremity of the stitch deflecting finger may also be formed with -a shallow thread receiving notch 104 to deter retrogression of a thread limb once the thread limb has been deflected to the free extremity of the finger 100. The needle thread of each stitch, both in forward stitches as illustrated in FIG. 5 and backward stitches as illustrated in FIG. 6, is thus deflected to one side of the line of needle penetration and the possibility of the needle penetrating the thread of a previous stitch is thus obviated. It is also pointed out that as illustrated in FIGS. 5 and 6, the stitch deflecting finger provides for a uniform appearance of the stitches in the seam.

Having thus set forth the nature of this invention, what I claim herein is:

1. In a sewing machine having a frame including a work supporting bed, a standa-rdrising from said bed, a bracket arm extending from said standard, and a sewing head formed on said bracket arm overhanging said bed, a needle carried on said sewing head and a loop taker carried in said bed, a main shaft journaled in said bracket arm, operative connections with said mainshaft for reciprocating said needle endwise and for imparting interrelated movement to said loop taker for the formation of lock stitches, a work feeding mechanism effective to transport work fabrics in one direction relatively to said work supporting bed, mean-s driven by said main shaft for operating said work feeding mechanism including an adjustable feed eccentric on said mainshaft, and a feed eccentric adjusting plunger carried in said bracket arm above said standard, a needle gate shiftably supported in said sewing head for movement in a plane parallel to the direction of transport of work fabrics by said work feeding mechanism, a rock shaft journaled in a partition between said bracket arm and said sewing head, a drive link affixed at one end to said rock shaft and slidably connected at the other end to said needle gate, and mechanism for jogging said needle gate including a bracket adapted to be secured on said bracket arm adjacent to said sewing head, a stud shaft journaled in said bracket, a driven gear and an adjustable needle jogging eccentric carried on said stud shaft, a drive gear fast on said main shaft and disposed in mesh with said driven gear when said bracket is secured on said bracket arm, a pitman embracing said adjustable eccentric, a rock arm operatively connecting said pitman to said rock shaft, and a needle jogging eccentric adjusting plunger carried on said bracket adjacent to said sewing head providing means for selecting an increment of needle gate shifting motion which is greater than the increment of feed during the formation of each stitch.

2. In a sewing machine having a frame including a support for a work fabric, said work support formed with an elongate needle aperture, a needle supported by said frame above of said work support and a loop taker carried by said frame beneath said work support for cooperating movement in the formation of lock stitches, actuating mechanism in said frame, operative connections with said actuating mechanism for reciprocating said needle endwise through said needle aperture and for imparting interrelated circular movement to said loop taker, a work feed ing mechanism effective to transport work fabrics across.

said work support in a direction parallel to said elongate needle aperture, means driven by said actuating mecha-- means driven by said actuating mechanism for vibrating said needle gate and including operator influenced means for selecting an increment of needle jogging motion along said needle aperture which is greater than the increment of work feed during the formation of each stitch, a stitch deflecting finger carried by said sewing machine frame sufficiently above said work support to accommodate a work fabric therebetween said stitch deflecting finger having a free extremity spanning said elongate needle aperture within said increment of needle jogging motion along said needle aperture.

3. In a sewing machine having a frame, including a work support formed with an elongate needle aperture, a needle and a loop taker carried by said frame for cooperating movement in the formation of lock stitches, actuating mechanism in said frame, operative connections with said actuating mechanism for reciprocating said needle endwise through said needle aperture and for imparting interrelated circular movement to said loop taker, a work feeding mechanism effective to transport work fabrics across said work support in a direction parallel to said elongate needle aperture, means driven by said actuating mechanism for operating said work feeding mechanism and including operator influenced means for selectively varying the increment of work feed imparted during the formation of each stitch, a needle gate shiftably supported on said sewing machine frame for movement in a plane parallel to said elongate needle aperture in said work support, means driven by said actuating mechanism for vibrating said needle gate and including operator influenced means for selecting an increment of needle jogging motion along said needle aperture which is greater than the increment of work feed during the formation of each stitch, a presser foot carried by said sewing machine frame, means biasing said presser foot against said work support adjacent to said needle aperture, and a stitch deflecting finger carried by said presser foot, said stitch deflecting finger having a free extremity spanning said elongate needle aperture within said increment of needle jogging motion along said needle aperture.

4. In a sewing machine having a frame, including a work support formed with an elongate needle aperture, a needle and a loop taker carried by said frame for cooperating movement in the formation of lock stitches, actuating mechanism in said frame, operative connections with said actuating mechanism for reciprocating said needle endwise through said needle aperture and for imparting interrelated circular movement to said loop taker, a work feeding mechanism effective to transport work fabrics across said work support in a direction parallel to said elongate needle aperture, means driven by said actuating mechanism for operating said work feeding mechanism and including operator influenced means for selectively varying the increment of work feed imparted during the formation of each stitch, a needle gate shiftably supported on said sewing machine frame for movement in a plane parallel to said elongate needle aperture in said work support, means driven by said actuating mechanism for vibrating said needle gate and including operator influenced means for selecting an increment of needle jogging motion along said needle aperture which is greater than the increment of work feed during the formation of each stitch, a presser foot carried by said sewing machine frame, means biasing said presser foot against said work support adjacent to said needle aperture, a stitch deflecting finger carried by said presser foot and formed with a free extremity spanning said elongate needle aperture within said increment of needle jogging motion along said needle aperture, said free extremity having a substantially flat undersurface arranged parallel to said sewing machine work support, a leading edge considered in the direction from which said work feeding mechanism transports work fabrics across said work support which is oblique to the direction of work feed being inclined in the direction of feed of a work fabric and toward the free extremity of said stitch deflecting finger, and an upper surface which is formed adjacent to the free extremity of said blade with a shallow thread accommodating notch.

References Cited by the Examiner UNITED STATES PATENTS 1,780,309 4/1930 Myers 112-459 1,840,571 1/1932 Eames 112l59 2,153,006 4/ 1939 Roseman 1112- 213 X 2,329,681 9/1943 Zeier 112213 2,706,460 4/1955 Grossman 112-235 2,980,044 4/ 1961 Parry 112-154 FOREIGN PATENTS 106,452 5/1917 Great Britain.

ROBERT V. SLOAN, Primary Examiner. 

1. IN A SEWING MACHINE HAVING A FRAME INCLUDING A WORK SUPPORTING BED, A STANDARD RISING FROM SAID BED, A BRACKET ARM EXTENDING FROM SAID STANDARD, AND A SEWING HEAD FORMED ON SAID BRACKET ARM OVERHANGING SAID BED, A NEEDLE CARRIED ON SAID SEWING HEAD AND A LOOP TAKER CARRIED IN SAID BED, A MAIN SHAFT JOURNALED IN SAID BRACKET ARM, OPERATIVE CONNECTIONS WITH SAID MAINSHAFT FOR RECIPROCATING SAID NEEDLE ENDWISE AND FOR IMPARTING INTERRELATED MOVEMENT TO SAID LOOK TAKER FOR THE FORMATION OF LOCK STITCHES, A WORK FEEDING MECHANISM EFFECTIVE TO TRANSPORT WORK FABRICS IN ONE DIRECTION RELATIVELY TO SAID WORK SUPPORTIN BED, MEANS DRIVEN BY SAID MAIN SHAFT FOR OPERATING SAID WORK FEEDING MECHANISM INCLUDING AN ADJUSTABLE FEED ECCENTRIC ON SAID MAINSHAFT, AND A FEED ECCENTRIC ADJUSTING PLUNGER CARRIED IN SAID BRACKET ARM ABOVE SAID STANDARD, A NEEDLE GATE SHIFTABLY SUPPORTED IN SAID SEWING HEAD FOR MOVEMENT IN A PLANE PARALLEL TO THE DIRECTION OF TRANSPORT OF WORK FABRICS BY SAID WORK FEEDING MECHANISM, A ROCK SHAFT JOURNALED IN A PARTITION BETWEEN SAID BRACKET ARM AND SAID SEWING HEAD, A DRIVE LINK AFFIXED AT ONE END TO SAID ROCK SHAFT AND SLIDABLY CONNECTED AT THE OTHER END TO SAID NEEDLE GATE, AND MECHANISM FOR JOGGING SAID NEEDLE GATE INCLUDING A BRACKET ADAPTED TO BE SECURED ON SAID BRACKET ARM ADJACENT TO SAID SEWING HEAD A STUD SHAFT JOURNALED IN SAID BRACKET, A DRIVEN GEAR AND AN ADJUSTABLE NEEDLE JOGGING ECCENTRIC CARRIED ON SAID STUD SHAFT, A DRIVE 